Pixel circuit, display device, and driving method thereof

• US 20080225027A1
• Filed: 03/11/2008
• Published: 09/18/2008
• Est. Priority Date: 03/16/2007
• Status: Abandoned Application

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Uchino, Katsuhide, Iida, Yukihito, Toyomura, Naobumi
• Application Number:
  US12/073,893
• Publication Number:
  US 20080225027A1
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

Disclosed herein is a display device including a pixel array unit and a control unit.

Claims

1. A display device comprising:

a pixel array unit configured to include pixel circuits arranged in a form of a matrix, said pixel circuits each including a drive transistor for generating a driving current, an electrooptic element connected to an output terminal of said drive transistor, a storage capacitor for retaining information corresponding to a signal potential of a video signal, a sampling transistor for writing the information corresponding to said signal potential to said storage capacitor, and a capacitive element having one terminal connected to the output terminal of said drive transistor and having another terminal supplied with a pulse signal, said drive transistor generating the driving current based on the information retained in said storage capacitor and sending the driving current through said electrooptic element, whereby said electrooptic element emits light; and

a control unit configured to include a writing scanning unit for outputting, to said sampling transistor, a writing scanning pulse for performing line-sequential scanning of said pixel circuits by sequentially controlling said sampling transistor in a horizontal period and writing information corresponding to a signal potential of a video signal to each of storage capacitors in one row, and a horizontal driving unit for supplying a video signal for one row to a video signal line according to a signal potential writing operation of said sampling transistor;

wherein said control unit effects control to perform mobility correcting operation for, after said sampling transistor is set in a conducting state and the information corresponding to said signal potential is retained in said storage capacitor, adding an amount of correction for mobility of said drive transistor to the information written in said storage capacitor while said sampling transistor is held in the conducting state, the other terminal of said capacitive element is supplied with information corresponding to a pulse for starting said mobility correcting operation, and

the output terminal of said drive transistor is supplied via said capacitive element with transition information in a direction of increasing a potential difference between a control input terminal and the output terminal of said drive transistor.

2. The display device according to claim 1, further including a light emission controlling transistor for adjusting a duty ratio between an emission period and a non-emission period of said electrooptic element,

wherein a scanning driving pulse supplied to a control input terminal of said light emission controlling transistor is set as the pulse for starting said mobility correcting operation.

3. The display device according to claim 1, further including a light emission controlling transistor of one of an n-type and a p-type, for adjusting a duty ratio between an emission period and a non-emission period of said electrooptic element, said light emission controlling transistor being disposed on a power supply terminal side of said drive transistor of the other of said n-type and said p-type,

wherein the other terminal of said capacitive element is connected to a control input terminal of said light emission controlling transistor, and

a scanning driving pulse supplied to the control input terminal of said light emission controlling transistor is set as the pulse for starting said mobility correcting operation.

4. The display device according to claim 1,

wherein said control unit effects control to make said sampling transistor conduct in a time period in which a reference potential is supplied to said sampling transistor and perform threshold value correcting operation for retaining a voltage corresponding to a threshold voltage of said drive transistor in said storage capacitor, and after the threshold value correcting operation, said control unit effects control to perform the mobility correcting operation for adding the amount of correction for the mobility of said drive transistor to the information written in said storage capacitor.

5. The display device according to claim 4,

wherein said pixel circuits each include a switch transistor performing on/off operation on a basis of a control pulse at a time of said threshold value correcting operation and said mobility correcting operation by said control unit in addition to said drive transistor and said sampling transistor.

6. A pixel circuit comprising:

a drive transistor configured to generate a driving current;

an electrooptic element connected to an output terminal of said drive transistor;

a storage capacitor configured to retain information corresponding to a signal potential of a video signal;

a sampling transistor configured to write the information corresponding to said signal potential to said storage capacitor; and

a capacitive element configured to have one terminal connected to the output terminal of said drive transistor;

wherein another terminal of said capacitive element is supplied with transition information in a direction of increasing a potential difference between a control input terminal and the output terminal of said drive transistor, said transition information corresponding to a pulse for starting mobility correcting operation for adding an amount of correction for mobility of said drive transistor to the information written in said storage capacitor.

7. A driving method of a pixel circuit, said pixel circuit including a drive transistor for generating a driving current, an electrooptic element connected to an output terminal of said drive transistor, a storage capacitor for retaining information corresponding to a signal potential of a video signal, a sampling transistor for writing the information corresponding to said signal potential to said storage capacitor, and a capacitive element having one terminal connected to the output terminal of said drive transistor and having another terminal supplied with a pulse signal, said drive transistor generating the driving current based on the information retained in said storage capacitor and sending the driving current through said electrooptic element, whereby said electrooptic element emits light, said driving method comprising the step of:

when said sampling transistor is set in a conducting state and the information corresponding to said signal potential is retained in said storage capacitor, and then mobility correcting operation for adding an amount of correction for mobility of said drive transistor to the information written in said storage capacitor is performed while said sampling transistor is held in the conducting state, supplying information corresponding to a pulse for starting said mobility correcting operation to the other terminal of said capacitive element, whereby a potential difference between a control input terminal and the output terminal of said drive transistor is increased.

8. A display device comprising:

pixel array means for including pixel circuits arranged in a form of a matrix, said pixel circuits each including a drive transistor for generating a driving current, an electrooptic element connected to an output terminal of said drive transistor, a storage capacitor for retaining information corresponding to a signal potential of a video signal, a sampling transistor for writing the information corresponding to said signal potential to said storage capacitor, and a capacitive element having one terminal connected to the output terminal of said drive transistor and having another terminal supplied with a pulse signal, said drive transistor generating the driving current based on the information retained in said storage capacitor and sending the driving current through said electrooptic element, whereby said electrooptic element emits light; and

control means for including a writing scanning unit for outputting, to said sampling transistor, a writing scanning pulse for performing line-sequential scanning of said pixel circuits by sequentially controlling said sampling transistor in a horizontal period and writing information corresponding to a signal potential of a video signal to each of storage capacitors in one row, and a horizontal driving unit for supplying a video signal for one row to a video signal line according to a signal potential writing operation of said sampling transistor;

wherein said control means for effects control to perform mobility correcting operation for, after said sampling transistor is set in a conducting state and the information corresponding to said signal potential is retained in said storage capacitor, adding an amount of correction for mobility of said drive transistor to the information written in said storage capacitor while said sampling transistor is held in the conducting state,

the other terminal of said capacitive element is supplied with information corresponding to a pulse for starting said mobility correcting operation, and

the output terminal of said drive transistor is supplied via said capacitive element with transition information in a direction of increasing a potential difference between a control input terminal and the output terminal of said drive transistor.